[flat grind with no distal taper]
Gryffin said:
...with modern CNC grinding gear, I can't imagine why it isn't done more.
It is less work to leave out a distal taper, most prefer a taper to produce a fine tip while giving a strong base near the choil. It makes the knife more versatile and there are also balance issues with larger knives, and likely with folders with very large blades as well. You don't tend to find flat grinds with no taper because no taper generally implies a cheaper construction and this is more suited to shallow sabre hollow grinds.
The Buck/Strider I referenced is this knife :
http://www.physics.mun.ca/~sstamp/images/strider_folder_side.jpg
It has no distal taper, nor even a point taper, it was similar to the old style points on the hollow ground models like the WB, they went from full stock to point in a small fraction of an inch. Very strong blade profile, most of it is at full stock. However due to the lock instability the massive blade is of little use because any work which takes advantage of the blades strength is likely to disengage or even break the lock.
Gryffin said:
Weed or cardboard? With a total POS $2 Chinese liner lock, perhaps;
Those two came from Joe, you can ask him for the details, being the guy who wrote the FAQ he got a lot of reports over the years as well as personally demonstrated problems with spine impacts and torques, mainly on liners. He generally does not do the extreme levels of force testing that is often implied by some when complaining about such work however still had lots of problems, and yes even with high end locks.
What you're describing requires the entire handle, and hence the liner, to flex significantly.
No, it is an issue with the liner, just like you can release the liner with your finger without causing the handle to flex at all.
The statistically-questionable sample size (one). You assume that your results on a single sample are indicative of every example of that model out there ...
Not only do I not do that, I take many steps to confirm this isn't the case by talking to the makers/manufacturers and comparing the results to other knives I have used. Note in this particular case Mike Strider confirmed that the behavior I saw with the Buck/Strider was to be expected so it isn't a one shot sample any more.
If I use a knife and see performance for which the maker contends are not representative then obviously I got a flawed sample so I either have it fixed or replaced and repeat the work. I have done both at times, just like I have done larger sample testing. It takes awhile of repeated behavior before I come to a fairly set viewpoint.
I didn't use one liner/integral and then write them off, I used many, of varying costs as well talked to guys like Joe and Steve who have done more work still, and then discussed it with makers/manufactures looking to find someone who would directly say their product didn't have those problems (in public of course).
In general low sample testing is less than ideal, but you have to live with it at times (and yes even in published work, monetary costs usually). With my work with knives it is a problem at times, I used a folder recently and the lock loosened during light chopping, it was a new line so the first thing that comes to mind is a potential problem.
So do I jump on the forums and exclaim it is defective, no. I tried two others from the same line, no problem, even pushed them further. I note all of that in the review as well as the maker contact information, and lately have been adding in the pass around threads. If I didn't have the other models on hand I'd ask the maker and talk to guys I know who use them significantly and see how they fared.
Of course even when the makers don't contend the results I compare them to other knives and steels, it doesn't need to be the same thing as many steels are in the same class so the behavior should not be dramatically different. Plus you can also compare different steels, if you note a problem with steel A and don't see the problem in B and B is worse than A materials wise, then that shows there is likely a problem with A.
Cumulative effects of near-destructive tests.
This is a problem, A. G. Russell wanted me to do work with some Deerhunters to show just what it would take to break them, the first thing that comes to mind is any impact work will lower any flex work. I have a couple of trainers (folding knives) I will be looking at lock security with soon with my brother and I want to see if you can do full dynamic stabs on a moving target, back cuts on a moving target, static spine impacts with a baton, and actual blocks with the spine (this is how I would rank them in order of increasing difficulty for the folder). All of these could cause the lock to release, and at very least could lower the performance in follow up work. Thus I'll have to take this into consideration.
Likewise with the Buck/Strider, isn't it possible that previous near-destructive testing led to the failure of the locking liner?
The liner failed due to a shear across the face, it had not been subjected to significant impacts before, or at any time, or used for prying or other singificant work, it was in fact just just used to cut rope and woods to determine its cutting ability NIB and with a modified edge profile. I could do the same thing with a SAK. As noted, the behavior of the lock under the torques+prying was noted to be as expected from the designer of the knife, Mick Strider, he noted this publically on the forums.
It doesn't matter how thick the liner is either, this doesn't make them significantly more stable, nor would it help prevent the face cracking as seen on the Buck/Strider. Raw strength is rarely an issue, it is security that usually limits use. Huge thick liners are more for speed hole effect than functionality, very thin liners can be very secure, Joe noted this years ago.
Note that in only the last case does the locking mechanism take the primary load.
It doesn't need to take the primary load, it doesn't even need to take a significant fraction of it. I have seen lots of releases where the blade never flexed at all, let alone significantly. Again, the releases that people talk about don't require forces which are of the same class as what is required to damage the blade or handle, they are not even of the same class, hence the ability to unlock with a pop off the palm or just twisting in cardboard. the disengagements I have seen happen in use that I easily could do with the Kershaw Vapor and not damage the blade.
... so you're actually undercutting your own argument that the Manix is more secure than the Strider.
No knife is directly 100% better without exception than any other knife, simply because every material and geometry has various advantages and disadvantages. Lockbacks can make certain grips problematic if the fingers come across the bar (ice pick), liners/integrals do the same thing and the grips are generally the more common ones (hammer and sabre) and they have the additional problems with impacts/torques which in general are not issues with lockbacks, thus overall they are more secure.
Oddly, too, in the same discussion you rejected the CRK&T LAWKS secondary lock as worthless, when functionally it does the same thing!
No it doesn't because it is thin unhardened steel whereas the bolt on the Fulcrum is a hardened very thick pin. That is like saying a mild steel blade and a hardened tool steel blade functionally do the same thing.
But advocating to others that it's acceptable behavior is just plain irresponsible; you sound like a shooter who claims that because a certain auto pistol has a firing pin safety, grip safety and a manual safety, waving it at people while pulling the trigger is perfectly safe and acceptable.
There is a difference, the safety on a gun is just that a safety, unlike the locks on an extension ladder for example which are needed for the ladder to actually function. You use these things all the time and if they fail you are at risk of losing more than your fingers.
While some will take the approach that locks on folders should be treated as they can disengage at any time, this is not how locks in general are expected to behave, there is a large difference between a safety and a lock, and knife manufactures/makers promote them as locks.
Mick Strider for example advocates extreme voilent jack hammer stabs to the face (a hard target which will result in a violent impact of steel on bone) for martial purposes and sells tactical/fighting folders. This can put a very heavy load directly against the lock as well as a very sharp and dynamic spine impact and torque as well.
I don't also advocate that you use a knife in a particular manner, I do what I do after evaluating the knife and take steps when doing so to account for failure. Once I know what it can do I use it accordingly. Same as I do with anything I depend on in general, knives are no different than any other tool in that regard.
What I do advocate is that makers/manufacturers should have their knives live up to the ways they are promoted, locks and everything else.
-Cliff